# Resource groups

**URL:** <https://discourse.chef.io/t/resource-groups/2230>\
**Category:** Chef Infra (archive)\
**Created:** [November 7, 2011, 5:58pm UTC](https://discourse.chef.io/t/resource-groups/2230 "2011-11-07T17:58:11Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![Maxim\_Kulkin](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.chef.io/maxim_kulkin/32/781_2.png) [@Maxim\_Kulkin](https://discourse.chef.io/u/Maxim_Kulkin)\
**Post date:** [November 7, 2011, 5:58pm UTC](https://discourse.chef.io/t/resource-groups/2230/1 "2011-11-07T17:58:11Z")

</div>

Hi everybody,

I’m pretty new to Chef and would like assistance for the following problem.  
I have a service and several configuration files for it. My other recipes communicate with that service, so it should be configured and ready to use before running them. I have following structure:

service ‘myservice’ do  
action :nothing  
end

template ‘/path/to/service/config1’ do  
…  
notifies :restart, resources(:service =\> ‘myservice’), :immediate  
end

template ‘/path/to/service/config2’ do  
…  
notifies :restart, resource(:service =\> ‘myservice’), :immediate  
end

service ‘myservice’ do  
action [:start, :enable]  
end

So, I want that if any of two configs change, the service is restarted not later than the second “service” resource. But in configuration that shown above, if both configs change, the service will be restarted two times.

How would you solve this “the Chef-way” ?

After reading through Chef sources I’ve developed following solution. I have a special resource – “resource\_group”:

service ‘myservice’ do  
action :nothing  
end

resource\_group ‘myservice\_configs’ do  
template ‘/path/to/service/config1’ do  
…  
end

```
template '/path/to/service/config2' do
  ...
end

notifies :restart, resource(:service => 'myservice'), :immediate

```

end

service ‘myservice’ do  
action [:start, :enable]  
end

So, when it is defined, it records all resources (through “method\_missing” magic) that are created inside of it. The resource\_group resource itself is created after resources in it (that’s how Chef works). One resource\_group’s action triggers, it checks embedded resources’ #updated? method and if any resource was updated, it set’s it’s own #updated\_by\_last\_action to true (thus triggering notifications).  
What do you think about this solution? Maybe it could make it into Chef core?

Thanks,  
Max

---

<div class="post-metadata">

**Author:** ![Dmitry\_Zamaruev](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dmitry\_Zamaruev](https://discourse.chef.io/u/Dmitry_Zamaruev)\
**Post date:** [November 7, 2011, 6:01pm UTC](https://discourse.chef.io/t/resource-groups/2230/2 "2011-11-07T18:01:56Z")

</div>

Why not get rid of immediate suffix ?  
In that case all :restart attempts will be grouped and service will be  
restarted only once. But not immediate, some where near to the end of  
recipe.

On Mon, 7 Nov 2011 21:58:11 +0400, Maxim Kulkin wrote:

> Hi everybody,
> 
> I'm pretty new to Chef and would like assistance for the following  
> problem.  
> I have a service and several configuration files for it. My other  
> recipes communicate with that service, so it should be configured and  
> ready to use before running them. I have following structure:
> 
> service 'myservice' do  
> action :nothing  
> end
> 
> template '/path/to/service/config1' do  
> ...  
> notifies :restart, resources(:service =\> 'myservice'), :immediate  
> end
> 
> template '/path/to/service/config2' do  
> ...  
> notifies :restart, resource(:service =\> 'myservice'), :immediate  
> end
> 
> service 'myservice' do  
> action [:start, :enable]  
> end
> 
> So, I want that if any of two configs change, the service is  
> restarted not later than the second "service" resource. But in  
> configuration that shown above, if both configs change, the service  
> will be restarted two times.
> 
> How would you solve this "the Chef-way" ?
> 
> After reading through Chef sources I've developed following solution.  
> I have a special resource -- "resource\_group":
> 
> service 'myservice' do  
> action :nothing  
> end
> 
> resource\_group 'myservice\_configs' do  
> template '/path/to/service/config1' do  
> ...  
> end
> 
> ```
> template '/path/to/service/config2' do
> ...
> end
> 
> notifies :restart, resource(:service => 'myservice'), :immediate
> 
> ```
> 
> end
> 
> service 'myservice' do  
> action [:start, :enable]  
> end
> 
> So, when it is defined, it records all resources (through  
> "method\_missing" magic) that are created inside of it. The  
> resource\_group resource itself is created after resources in it  
> (that's how Chef works). One resource\_group's action triggers, it  
> checks embedded resources' #updated? method and if any resource was  
> updated, it set's it's own #updated\_by\_last\_action to true (thus  
> triggering notifications).  
> What do you think about this solution? Maybe it could make it into  
> Chef core?
> 
> Thanks,  
> Max

---

<div class="post-metadata">

**Author:** ![Dmitry\_Zamaruev](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dmitry\_Zamaruev](https://discourse.chef.io/u/Dmitry_Zamaruev)\
**Post date:** [November 7, 2011, 6:04pm UTC](https://discourse.chef.io/t/resource-groups/2230/3 "2011-11-07T18:04:32Z")

</div>

Good example in Apache2 recipe:  
[https://github.com/opscode/cookbooks/blob/master/apache2/recipes/default.rb](https://github.com/opscode/cookbooks/blob/master/apache2/recipes/default.rb)

On Mon, 07 Nov 2011 20:01:56 +0200, Dmitry Zamaruev wrote:

> Why not get rid of immediate suffix ?  
> In that case all :restart attempts will be grouped and service will  
> be restarted only once. But not immediate, some where near to the end  
> of recipe.
> 
> On Mon, 7 Nov 2011 21:58:11 +0400, Maxim Kulkin wrote:
> 
> > Hi everybody,
> > 
> > I'm pretty new to Chef and would like assistance for the following  
> > problem.  
> > I have a service and several configuration files for it. My other  
> > recipes communicate with that service, so it should be configured  
> > and  
> > ready to use before running them. I have following structure:
> > 
> > service 'myservice' do  
> > action :nothing  
> > end
> > 
> > template '/path/to/service/config1' do  
> > ...  
> > notifies :restart, resources(:service =\> 'myservice'),  
> > :immediate  
> > end
> > 
> > template '/path/to/service/config2' do  
> > ...  
> > notifies :restart, resource(:service =\> 'myservice'), :immediate  
> > end
> > 
> > service 'myservice' do  
> > action [:start, :enable]  
> > end
> > 
> > So, I want that if any of two configs change, the service is  
> > restarted not later than the second "service" resource. But in  
> > configuration that shown above, if both configs change, the service  
> > will be restarted two times.
> > 
> > How would you solve this "the Chef-way" ?
> > 
> > After reading through Chef sources I've developed following  
> > solution.  
> > I have a special resource -- "resource\_group":
> > 
> > service 'myservice' do  
> > action :nothing  
> > end
> > 
> > resource\_group 'myservice\_configs' do  
> > template '/path/to/service/config1' do  
> > ...  
> > end
> > 
> > ```
> > template '/path/to/service/config2' do
> > ...
> > end
> > 
> > notifies :restart, resource(:service => 'myservice'), :immediate
> > 
> > ```
> > 
> > end
> > 
> > service 'myservice' do  
> > action [:start, :enable]  
> > end
> > 
> > So, when it is defined, it records all resources (through  
> > "method\_missing" magic) that are created inside of it. The  
> > resource\_group resource itself is created after resources in it  
> > (that's how Chef works). One resource\_group's action triggers, it  
> > checks embedded resources' #updated? method and if any resource was  
> > updated, it set's it's own #updated\_by\_last\_action to true (thus  
> > triggering notifications).  
> > What do you think about this solution? Maybe it could make it into  
> > Chef core?
> > 
> > Thanks,  
> > Max

---

<div class="post-metadata">

**Author:** ![Maxim\_Kulkin](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.chef.io/maxim_kulkin/32/781_2.png) [@Maxim\_Kulkin](https://discourse.chef.io/u/Maxim_Kulkin)\
**Post date:** [November 7, 2011, 6:18pm UTC](https://discourse.chef.io/t/resource-groups/2230/4 "2011-11-07T18:18:30Z")

</div>

As I said, other resources use that service, so it needs to be configured immediately. If I make notifications delayed, the restart will be after other recipes get executed and thus resources in those other recipes won't be able to communicate with that service because of it's misconfiguration.  
Say, it's a web service and configuration files determine port and credentials to communicate with that service. If those values will change, but the service is not restarted, other recipes won't be able to access it.

On Nov 7, 2011, at 22:01, Dmitry Zamaruev wrote:

> Why not get rid of immediate suffix ?  
> In that case all :restart attempts will be grouped and service will be restarted only once. But not immediate, some where near to the end of recipe.
> 
> On Mon, 7 Nov 2011 21:58:11 +0400, Maxim Kulkin wrote:
> 
> > Hi everybody,
> > 
> > I'm pretty new to Chef and would like assistance for the following problem.  
> > I have a service and several configuration files for it. My other  
> > recipes communicate with that service, so it should be configured and  
> > ready to use before running them. I have following structure:
> > 
> > service 'myservice' do  
> > action :nothing  
> > end
> > 
> > template '/path/to/service/config1' do  
> > ...  
> > notifies :restart, resources(:service =\> 'myservice'), :immediate  
> > end
> > 
> > template '/path/to/service/config2' do  
> > ...  
> > notifies :restart, resource(:service =\> 'myservice'), :immediate  
> > end
> > 
> > service 'myservice' do  
> > action [:start, :enable]  
> > end
> > 
> > So, I want that if any of two configs change, the service is  
> > restarted not later than the second "service" resource. But in  
> > configuration that shown above, if both configs change, the service  
> > will be restarted two times.
> > 
> > How would you solve this "the Chef-way" ?
> > 
> > After reading through Chef sources I've developed following solution.  
> > I have a special resource -- "resource\_group":
> > 
> > service 'myservice' do  
> > action :nothing  
> > end
> > 
> > resource\_group 'myservice\_configs' do  
> > template '/path/to/service/config1' do  
> > ...  
> > end
> > 
> > template '/path/to/service/config2' do  
> > ...  
> > end
> > 
> > notifies :restart, resource(:service =\> 'myservice'), :immediate  
> > end
> > 
> > service 'myservice' do  
> > action [:start, :enable]  
> > end
> > 
> > So, when it is defined, it records all resources (through  
> > "method\_missing" magic) that are created inside of it. The  
> > resource\_group resource itself is created after resources in it  
> > (that's how Chef works). One resource\_group's action triggers, it  
> > checks embedded resources' #updated? method and if any resource was  
> > updated, it set's it's own #updated\_by\_last\_action to true (thus  
> > triggering notifications).  
> > What do you think about this solution? Maybe it could make it into Chef core?
> > 
> > Thanks,  
> > Max

---

<div class="post-metadata">

**Author:** ![Dmitry\_Zamaruev](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dmitry\_Zamaruev](https://discourse.chef.io/u/Dmitry_Zamaruev)\
**Post date:** [November 7, 2011, 6:29pm UTC](https://discourse.chef.io/t/resource-groups/2230/5 "2011-11-07T18:29:17Z")

</div>

I use following workaround:

ruby\_block "service\_changed" do  
block  
node["service\_changed"] = true  
node.save  
end  
end

ruby\_block "service\_restarted" do  
block  
node.delete("service\_changed")  
node.save  
end  
end

template "1" do  
notifies :create, "ruby\_block[service\_changed]", :immediately  
end

template "2" do  
notifies :create, "ruby\_block[service\_changed]", :immediately  
end

service "my\_service" do  
action :restart  
only\_if { node.attribute?("service\_changed") }  
notifies :create, "ruby\_block[service\_restarted]"  
end

As soon as control got to last service entry - it is restarted only if  
templates changed.  
If there would be native approach in Chef - it would be very nice.

On Mon, 7 Nov 2011 22:18:30 +0400, Maxim Kulkin wrote:

> As I said, other resources use that service, so it needs to be  
> configured immediately. If I make notifications delayed, the restart  
> will be after other recipes get executed and thus resources in those  
> other recipes won't be able to communicate with that service because  
> of it's misconfiguration.  
> Say, it's a web service and configuration files determine port and  
> credentials to communicate with that service. If those values will  
> change, but the service is not restarted, other recipes won't be able  
> to access it.
> 
> On Nov 7, 2011, at 22:01, Dmitry Zamaruev wrote:
> 
> > Why not get rid of immediate suffix ?  
> > In that case all :restart attempts will be grouped and service will  
> > be restarted only once. But not immediate, some where near to the end  
> > of recipe.
> > 
> > On Mon, 7 Nov 2011 21:58:11 +0400, Maxim Kulkin wrote:
> > 
> > > Hi everybody,
> > > 
> > > I'm pretty new to Chef and would like assistance for the following  
> > > problem.  
> > > I have a service and several configuration files for it. My other  
> > > recipes communicate with that service, so it should be configured  
> > > and  
> > > ready to use before running them. I have following structure:
> > > 
> > > service 'myservice' do  
> > > action :nothing  
> > > end
> > > 
> > > template '/path/to/service/config1' do  
> > > ...  
> > > notifies :restart, resources(:service =\> 'myservice'),  
> > > :immediate  
> > > end
> > > 
> > > template '/path/to/service/config2' do  
> > > ...  
> > > notifies :restart, resource(:service =\> 'myservice'), :immediate  
> > > end
> > > 
> > > service 'myservice' do  
> > > action [:start, :enable]  
> > > end
> > > 
> > > So, I want that if any of two configs change, the service is  
> > > restarted not later than the second "service" resource. But in  
> > > configuration that shown above, if both configs change, the service  
> > > will be restarted two times.
> > > 
> > > How would you solve this "the Chef-way" ?
> > > 
> > > After reading through Chef sources I've developed following  
> > > solution.  
> > > I have a special resource -- "resource\_group":
> > > 
> > > service 'myservice' do  
> > > action :nothing  
> > > end
> > > 
> > > resource\_group 'myservice\_configs' do  
> > > template '/path/to/service/config1' do  
> > > ...  
> > > end
> > > 
> > > template '/path/to/service/config2' do  
> > > ...  
> > > end
> > > 
> > > notifies :restart, resource(:service =\> 'myservice'), :immediate  
> > > end
> > > 
> > > service 'myservice' do  
> > > action [:start, :enable]  
> > > end
> > > 
> > > So, when it is defined, it records all resources (through  
> > > "method\_missing" magic) that are created inside of it. The  
> > > resource\_group resource itself is created after resources in it  
> > > (that's how Chef works). One resource\_group's action triggers, it  
> > > checks embedded resources' #updated? method and if any resource  
> > > was  
> > > updated, it set's it's own #updated\_by\_last\_action to true (thus  
> > > triggering notifications).  
> > > What do you think about this solution? Maybe it could make it into  
> > > Chef core?
> > > 
> > > Thanks,  
> > > Max

---

<div class="post-metadata">

**Author:** ![Maxim\_Kulkin](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.chef.io/maxim_kulkin/32/781_2.png) [@Maxim\_Kulkin](https://discourse.chef.io/u/Maxim_Kulkin)\
**Post date:** [November 8, 2011, 7:45am UTC](https://discourse.chef.io/t/resource-groups/2230/6 "2011-11-08T07:45:57Z")

</div>

Yes, I'm also aware of ability to pass data through node attributes, but this approach seems too heavy weight to me. I was experimenting with it and here is another solution that I've found:

service 'myservice' do  
action :nothing  
end

template '/path/to/service/config1' do  
...  
end

template '/path/to/service/config2' do  
...  
end

service 'myservice' do  
action [:start, :enable]  
end

service 'myservice' do  
action :restart  
only\_if {  
resources(:template =\> ['/path/to/service/config1', '/path/to/service/config2']).any?(&:updated?)  
}  
end

Alternatively, you can collect resources into an array during their creation:

myservice\_configs =   
myservice\_configs \<\< template('/path/to/service/config1') do  
...  
end  
myservice\_configs \<\< template('/path/to/service/config2') do  
...  
end

service 'myservice' do  
action :restart  
only\_if { myservice\_configs.any?(&:updated?) }  
end

And here is my solution with resource groups that I've mentioned earlier. You can put it into some cookbook's "libraries/resource\_group.rb" file:

[https://gist.github.com/1347238](https://gist.github.com/1347238)

On Nov 7, 2011, at 22:29, Dmitry Zamaruev wrote:

> I use following workaround:
> 
> ruby\_block "service\_changed" do  
> block  
> node["service\_changed"] = true  
> node.save  
> end  
> end
> 
> ruby\_block "service\_restarted" do  
> block  
> node.delete("service\_changed")  
> node.save  
> end  
> end
> 
> template "1" do  
> notifies :create, "ruby\_block[service\_changed]", :immediately  
> end
> 
> template "2" do  
> notifies :create, "ruby\_block[service\_changed]", :immediately  
> end
> 
> service "my\_service" do  
> action :restart  
> only\_if { node.attribute?("service\_changed") }  
> notifies :create, "ruby\_block[service\_restarted]"  
> end
> 
> As soon as control got to last service entry - it is restarted only if templates changed.  
> If there would be native approach in Chef - it would be very nice.
> 
> On Mon, 7 Nov 2011 22:18:30 +0400, Maxim Kulkin wrote:
> 
> > As I said, other resources use that service, so it needs to be  
> > configured immediately. If I make notifications delayed, the restart  
> > will be after other recipes get executed and thus resources in those  
> > other recipes won't be able to communicate with that service because  
> > of it's misconfiguration.  
> > Say, it's a web service and configuration files determine port and  
> > credentials to communicate with that service. If those values will  
> > change, but the service is not restarted, other recipes won't be able  
> > to access it.
> > 
> > On Nov 7, 2011, at 22:01, Dmitry Zamaruev wrote:
> > 
> > > Why not get rid of immediate suffix ?  
> > > In that case all :restart attempts will be grouped and service will be restarted only once. But not immediate, some where near to the end of recipe.
> > > 
> > > On Mon, 7 Nov 2011 21:58:11 +0400, Maxim Kulkin wrote:
> > > 
> > > > Hi everybody,
> > > > 
> > > > I'm pretty new to Chef and would like assistance for the following problem.  
> > > > I have a service and several configuration files for it. My other  
> > > > recipes communicate with that service, so it should be configured and  
> > > > ready to use before running them. I have following structure:
> > > > 
> > > > service 'myservice' do  
> > > > action :nothing  
> > > > end
> > > > 
> > > > template '/path/to/service/config1' do  
> > > > ...  
> > > > notifies :restart, resources(:service =\> 'myservice'), :immediate  
> > > > end
> > > > 
> > > > template '/path/to/service/config2' do  
> > > > ...  
> > > > notifies :restart, resource(:service =\> 'myservice'), :immediate  
> > > > end
> > > > 
> > > > service 'myservice' do  
> > > > action [:start, :enable]  
> > > > end
> > > > 
> > > > So, I want that if any of two configs change, the service is  
> > > > restarted not later than the second "service" resource. But in  
> > > > configuration that shown above, if both configs change, the service  
> > > > will be restarted two times.
> > > > 
> > > > How would you solve this "the Chef-way" ?
> > > > 
> > > > After reading through Chef sources I've developed following solution.  
> > > > I have a special resource -- "resource\_group":
> > > > 
> > > > service 'myservice' do  
> > > > action :nothing  
> > > > end
> > > > 
> > > > resource\_group 'myservice\_configs' do  
> > > > template '/path/to/service/config1' do  
> > > > ...  
> > > > end
> > > > 
> > > > template '/path/to/service/config2' do  
> > > > ...  
> > > > end
> > > > 
> > > > notifies :restart, resource(:service =\> 'myservice'), :immediate  
> > > > end
> > > > 
> > > > service 'myservice' do  
> > > > action [:start, :enable]  
> > > > end
> > > > 
> > > > So, when it is defined, it records all resources (through  
> > > > "method\_missing" magic) that are created inside of it. The  
> > > > resource\_group resource itself is created after resources in it  
> > > > (that's how Chef works). One resource\_group's action triggers, it  
> > > > checks embedded resources' #updated? method and if any resource was  
> > > > updated, it set's it's own #updated\_by\_last\_action to true (thus  
> > > > triggering notifications).  
> > > > What do you think about this solution? Maybe it could make it into Chef core?
> > > > 
> > > > Thanks,  
> > > > Max

---

<div class="post-metadata">

**Author:** ![kallistec](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.chef.io/kallistec/32/23_2.png) [@kallistec](https://discourse.chef.io/u/kallistec)\
**Post date:** [November 8, 2011, 3:39pm UTC](https://discourse.chef.io/t/resource-groups/2230/7 "2011-11-08T15:39:12Z")

</div>

On Monday, November 7, 2011 at 9:58 AM, Maxim Kulkin wrote:

> Hi everybody,
> 
> After reading through Chef sources I've developed following solution. I have a special resource -- "resource\_group":
> 
> What do you think about this solution? Maybe it could make it into Chef core?
> 
> Thanks,  
> Max

I replied over on the chef-dev list.

--  
Dan DeLeo

---

<div class="post-metadata">

**Author:** ![kallistec](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.chef.io/kallistec/32/23_2.png) [@kallistec](https://discourse.chef.io/u/kallistec)\
**Post date:** [November 8, 2011, 3:38pm UTC](https://discourse.chef.io/t/resource-groups/2230/8 "2011-11-08T15:38:13Z")

</div>

On Monday, November 7, 2011 at 9:58 AM, Maxim Kulkin wrote:

> Hi everybody,
> 
> I'm pretty new to Chef and would like assistance for the following problem.  
> I have a service and several configuration files for it. My other recipes communicate with that service, so it should be configured and ready to use before running them. I have following structure:
> 
> service 'myservice' do  
> action :nothing  
> end
> 
> template '/path/to/service/config1' do  
> ...  
> notifies :restart, resources(:service =\> 'myservice'), :immediate  
> end
> 
> template '/path/to/service/config2' do  
> ...  
> notifies :restart, resource(:service =\> 'myservice'), :immediate  
> end
> 
> service 'myservice' do  
> action [:start, :enable]  
> end
> 
> So, I want that if any of two configs change, the service is restarted not later than the second "service" resource. But in configuration that shown above, if both configs change, the service will be restarted two times.
> 
> How would you solve this "the Chef-way" ?
> 
> After reading through Chef sources I've developed following solution. I have a special resource -- "resource\_group":
> 
> service 'myservice' do  
> action :nothing  
> end
> 
> resource\_group 'myservice\_configs' do  
> template '/path/to/service/config1' do  
> ...  
> end
> 
> template '/path/to/service/config2' do  
> ...  
> end
> 
> notifies :restart, resource(:service =\> 'myservice'), :immediate  
> end
> 
> service 'myservice' do  
> action [:start, :enable]  
> end
> 
> So, when it is defined, it records all resources (through "method\_missing" magic) that are created inside of it. The resource\_group resource itself is created after resources in it (that's how Chef works). One resource\_group's action triggers, it checks embedded resources' #updated? method and if any resource was updated, it set's it's own #updated\_by\_last\_action to true (thus triggering notifications).  
> What do you think about this solution? Maybe it could make it into Chef core?
> 
> Thanks,  
> Max

This is the same solution I came up with to the problem: [http://tickets.opscode.com/browse/CHEF-2452](http://tickets.opscode.com/browse/CHEF-2452)

I think resource groups are actually useful for several things:

- better control over notifications
- failure zones: allow a group to fail without stopping the Chef run
- customizing recipes: include\_recipe could be extended so that only certain groups from a recipe are included. Also, groups could be overridden by a user of the recipe. Think of replacing the "install" group with resources to install a package from source.

In order to accomplish all of these, resource groups would have to be integrated pretty deeply into Chef's resource collection. But there's no reason we can't add groups now and iterate. We do need to be careful not to accidentally leak implementation that then becomes an API that users want to rely on.

--  
Dan DeLeo